Pull rod carrier



Dec. 4, 1945.l A. M. RossMAN PULL ROD CARRIER Filed OCT.. 50, 1942 3Sheets-Sheet 1 Dec. 4, 1945. A. M. RossMAN PULL ROD CARRIER Filed Oct.-30, 1942 3 Sheets-Sheet 2 Dec. 4, 1945. A M. RossMAN PULL ROD CARRIERFiled Qct. 30, 1942 3 Sheets-Sheet 3 Patented Dec. 4, 1945 UNITED STATESPATENT OFFICE PULL ROD CRRIER llen M. Rossman, Wilmet'te, Ill.

Application October 30, 1942, Serial No. 463,959

17 Claims.

This invention relates to pull rod carriers, and more particularly tocarriers of the type shown in my pending application, Serial No.272,865.

In certain oil well districts horizontally reciprocating pull rods areused for transmitting power from a central engine or source of power toeach of a plurality of pumps, some of which may be thousands of feetfrom the source of power. Each pull rodis supported by carriers everytwenty-five or so feet in order to prevent excessive sagging of the pullrod, or to'` prevent dragging on the ground. The pull rod carrier of thepresent invention comprises a series of pivotally interconnected linkssupported on a stationary support set into afoundation or foundations inthe ground and supporting the carrier and guiding it in a straight`horizontal line as the pull rod reciprocates. The reciprocatingmovement of the pull rod actuates the supporting linkage and althoughthe linkage reciprocates with the rod the parts of the linkage thatdirectly support the rod move in substantially a straight line.

The supporting carrier' of the present invention comprises twoside linksor arms pivotally connected at their upper and lower ends to upper andlower bars or links of unequal size to form a quadijilateral. The loadplaced on the carrier by the rod is supported by thev side arms orlinks. It is one of the objects of the present invention to provide aconstruction of the side arms or links such as will not be subjected tobending or tor.- sion stress so that all of the stress therein will beeither 4tensile or compressive stress. This is accomplished, in thepreferred construction, by making each link in the form of a pair ofbalanced members which are spaced equally on op'- posite sides of thepath of motion of the pull rod and thus eliminate all bending stressesin those members. This makes for stability of operation and even wear onthe bearings.

It is a further object of the present invention to provide a carrierwherein the bearing parts are al1 woodand an integral part of one or theotherof the two linkage members that are journalled together at thebearing. By this arrange'- Inent the bearings cannot rock with respectto the carrier. This further reduces the possibility of wearing enlargedholes at the bearings. Furthermore, by this arrangement the bearingholes can be drilled in the wooden members to the correct dimensions,thereby producing a strucune which is true initially and permanently.Steel members that are bent to shape to support the bearings are notalways bent true and may not always retain the true shape.

It is a still further object of lthe pre s ent invention to provide apull rod carrier wherein` certain parts that are made of steel may bemade in a simple and economical manner and be sturdy of construction.

The attainment ofthe above and further objects of the present inventionwill be apparent from the following specification takenin conjunctionwith the accompanying drawings forming a part thereof.

In the drawings:

Figure 1 is a top view of a pull rod carrier embodying the presentinventiorif Figure 2 is a side view of the carrier of Figure 1; y

Figure 3 is a sectional View Vtaken along the line 3--3 of Figure 2 andlooking in the direction ofthe arrows; ,A

Figure 4 is an end View f the carrier of Figure 2; e

Figure 5 is an enlarged sectional vview taken along the line 5 5 ofFigure 1 and looking in tlie direction of the arrow s;

' perspective View of a carrier Figure 5a is a supporting block;

Figure 6 is a top view of a modied'form of cross member;

Figure '7 is a fragmentary sectional view taken along the line 1-1 ofFigure 6;

Figure 8 is an end view of an alternatey pivotal' connection at thebottom of the side arms of the carrier of Figure 2;

Figure 9 is a front view showing a modified forni o'f carriercorresponding to Figure 2;

' Figure 10 is an enlarged fragmentary sectional view of a portion ofFigure 9;

Figure 11 is a top view of still another carrier embodying the presentinvention;

Figure 12 is a side view of the carrier of Figure 11;

Figure 13 is a sectional view taken along the line l3-I3 of Figure 12;and

Figure 14 is a sectional view line |4--I4r of Figure 12. Y

In the various figures of drawings like reference numerals designatelike parts throughout. Reference may now be had more particularly to theembodiment of the invention illustrated in Figures 1, 2, 3 and 4. Aportion of a horizontally reciprocating pull rod is illustrated at l.The pull rod may be several thousand feet in length and is reciprocatedto transmit power from a source of power to a pump of an oil well, andis supported above the ground every twentyfive feet or so by a carriersuch as the carrier 2. The carrier is mounted on a single supportcomtaken along the prlsing a vertical pipe 3 of steel or the like, whichis firmly set into the ground or in a foundation in the ground. Thefoundation pipe 3 is open at the top and receives the stem 4 of aT-shaped wooden support 5 the web of which is indicated at 6. The stem 4of the support may be an integral part of the web 6, and is circular incross section and makes snug driven fit in the pipe 3. The web 6 of thesupport 5 has a horizontal bore I formed therethrough which constitutesa support for a bearing pin or tube 8 that is the pivot upon which thecarrier is supported and about which it swings.

The carrier 2 includes a cross member I0 in the form of a wooden beamhaving four parallel holes formed transversely therein. Two of the holesare provided for receiving bolts II and I2 and are located midwaybetween the top and bottom surface thereof as seen in Figure 2. Theother two holes, of which more will be stated as this descriptionproceeds, are holes for receiving pivot tubes I4 and I5. These holes arenot l0- 'cated on the longitudinal center of the member I0 but rather ashort distance above the longitudinal center so that there isappreciably more wood of the beam I0 below the holes forV the pivottubes I4 and I5 than above them, for a reason which will be apparent asthis description proceeds. The bolts II and I2 rigidly secure two pairsof wooden struts II-II and I8-I8 to the cross member I0. The pair ofstruts I'I diverge from the cross member I0 and the pair of struts I8also diverge from the cross member I0, as may be seen in Figure 1. Thetwo pairs of struts converge towards one another, as may be seen inFigures 1 and 2, and extend on opposite sides 9-9 of the support 5. Thetwo pairs of struts are secured together by the pivot tube 8. It is thusapparent that the cross member I0 and the four struts II-I'I and I8-I 8constitute one rigid structure pivoted about the center of the tube 8.The struts II-II and I6-I8 are chamfered off at their top ends as may beseen more fully in Figure 5, to facilitate bolting of the ends of thestruts to the cross member I0.

Identical links -2I are pivoted at their upper ends to the bar I0 by thepivot'tubes I4-I5. Each of the links 20-2I comprises a pair of woodenside bars 22-22 that are spaced a fixed distance on opposite sides ofthe cross bar I 8 by identical Wood spacer blocks 23-23 that are boredto receive the pivot tubes I4 or I5, as the case may be. At their lowerends the links 20-2I are pivoted to a bottom link 25 by pivot tubes 26,the side bars of the links 20 being spaced from the link 25 by woodenspacer blocks 21-2`I, shown more particularly in Figure 4. The spacerblocks 21-21 have holes formed therein through which the associatedpivot tube 26 extends. addition, each of the blocks 21-21 overlies aportion of the top of the link 25, as may be seen from Figure 4, thespace between the adjacent blocks 21-21 at the top of the link 25 beingjust sufficient to allow the pull rod I to t between the blocks and reston the link or bar 25. The links 20--2I thus support the link 25 uponwhich the rod I rests, and the rod is prevented from shifting sidewiseon the link 25 by the spacer blocks 2'I-2I while permitting freedom ofsliding movement of the rod lengthwise of the link 25.

The pivot tubes 8, I4, I5 and 26 are held in place against sliding outof the bearings in any desired manner as, for instance, by small wiresor pins 29 each of which is passed through aligned InA holes in the endof the tube and then bent to hold it in place.

All wood parts are rough cut and thoroughly dried and then soaked incrude oil before being put into service. The bearings are lubricatedwith a heavy grease before assembling the carriers. Thereafter nosubsequent lubrication is required.

It is to be noted that the link 25 extends an appreciable distancebeyond the links 20-2I on opposite'sides of the carrier, and supportsthe rod I at the portions 32-32 beyond the linkage. The proportions ofthe links are such that With the pivot axis 8 stationary, then so longas the pivots 26-26 are maintained in horizontal alignment theirdirection of movement as the linkage is actuated will be insubstantially a straight horizontal line. The weight of the pull roditself maintains the link 25 horizontal by reason of the extensions32-32. Any tendency for the left hand pivot 26 to drop below that of theright hand pivot 26 would result in tilting of the link 25 and raisingof the right hand end extension 32. The weight of the rod itselfprevents such rise and thereby prevents either pivot 26 from droppingbelow the level of the other pivot 26.

In the carrier illustrated in Figure 2 the overall complete length ofthe link 25 is seven feet. If the length of unsupported portions of thepull rod I between adjacent carriers is to be twentyfive feet, by Way ofexample, then the center to center distance between foundation posts 3for adjacent carriers would be made thirtytwo feet.

As the pull rod moves, for instance, to the left from the positionillustrated in full lines in Figure 2, the carrier 2 moves from the fullline position of that figure to the dotted line position. When itreaches the dotted line position the side bars of the link 2I abutagainst the web 6 of the T-support 5 or against the lower ends of thestruts I'I-II and thus hold the carrier against further swinging aboutthe pivot 8. Continued movement of the rod I to the left results merelyin sliding of the rod I along the link 25 until the rod reaches the endof its stroke. Thereafter, on reverse horizontal movement of the rod Ithe linkage 2 tilts from the dotted line position of Figure 2 back tothe full line position and then continues tilting to another position onthe opposite side of the center 8 corresponding to the dotted lineposition here illustrated. The stroke of the straight line motionmechanism is twice the distance of travel of the pivot 26 of the link 2|from the full line position of Figure 2 to the dotted line position ofFigure 2. The linkage is designed so that its full stroke is slightly inexcess of the amplitude of the stroke of the reciprocating pull rod I.Thus during the initial movement of the pull rod after assembly of thecarrier the pull rod adjusts itself on the carrier by sliding along thecarrier after the carrier has reached its limiting stop position. Oncethis adjustment has been made continued reciprocation' of the pull rodresults in a corresponding to and fro movement of the link 25 with nosliding movement between the pull rod and the link 25 of the carrier.The pull rod is thus supported and guided in its reciprocating movementwithout any sliding of the pull rod.

During the major portion of the cycle of travel of the pull rod theweight thereof places the links 28 and 2l in tension so that the tubesI4-I 5 are exerting their pressure on the bottom surfaces of the bearingholes in the cross member I0. Those surfaces of the bearings thereforereceive the most wear, and for that reason the holes for the bearingsI4-I5 in the member IIJ are placed slightly above the center of themember to provide more material below the bearings where wear takesplace. On the other hand, at the bearings 26-26 of the link 25 the link25 exerts its pressure on the bearing tubes at the top surfaces of thebearing holes during the major part of the cycle of travel of the pullrod. The major wear therefore takes place at the top surfaces of thebearing holes in the link 25, and the bearing holes are thereforelocated below the center of that link to provide more material above thebearing holes, where the wear takes place.

Figure 6 showsv an alternate construction of the cross member IIJ. Inthis construction the cross member is indicated at I'. At its oppositeends the bar or cross member I0' has enlarged heads 38-38 through whichholes 39-39 are formed for receiving the pivot Itubes I4 and I5,respectively. 'Ihe cross member I8 may be made from a single woodenmember cut out to the shape illustrated in Figure 6. When this is donethe sides of the cross member I0' may be cutat an angle, as illustratedin Figure '7, and the upper ends of the struts I1-I8 need not bechamfered. The enlarged heads 39 provide the necessary spacing for theside bars 22-22 thus eliminating the need for the upper spacers 23-23 ofFigures l and 4. Also, spacers 21--21 at the lower ends of the bars22-22 may be replaced by a single rectangular wooden spacer block 21',as illustrated in Figure 8. The spacer block 21 extends between the bars22-22 and is pivoted on the pivotl tube 26. The link 25 is thensupported by the two spacer blocks 21 one of which is located at thebottom of the side bars of the link 20 and the other of which is locatedat the bottom of the side bars of the link 2|. The link 25 is secured toeach spacer bar 21 by two sets of side by side bolts 40-40 each of whichextends through the spacer block 21' and through the link 25 and a shortdistance above the link 25 so that the spaced Shanks of the bolts,indicated at 4 I-4I in Figure 8, hold the rod I against sidewisemovement orf of the link 25. The bolts 45 -are kept in place by nutsthreaded thereon and resting in countersunk holes at the top of the link25.

In the embodiments of the invention illustrated in Figure 2 each carrieris supported by a single support. Some terrain encountered is such thatit is more economical to use two supports than to attempt to obtain therequisite rigidity from a single support. When this is the case thecarrier of Figure 2 can be mounted in a somewhat diierent manner, asillustrated in Figure 9. In

- this ligure two supports 3 3, of the same construction as previouslydescribed in Figure 2, are mounted in the ground in alignment, a properdistance apart, and each has at the top thereof a T-shaped support 5. Inthis instance the link 25 of Figure 2 is omitted, and the side bars ofthe links ZII--ZI are pivoted to the stationary supports 5 by the pivottubes 8a and 8b, each of which extends through the bearing hole 1 in oneof the supports 5. Ihe links 2D and 2l are connected together at theirupper ends by the cross member II! which has the struts I1 and I8secured thereto in a manner previously described, and carries a support42 in the form of a block located between the two struts I1-I1 and thetwo struts I8-I8 and pivoted between the struts by a tube 43. In thisconstruction the distance between the pivots 8a8b is made'proportionately longer than between the pivots- 26--26 of Figure 2 inorder lto allow the foreshortening of thestruts I'I-IB to bring thepivot point 42 above the pivots Sci- 8b while maintaining the straightline motion characteristics of the carrier. The distances between thepivots 8a and I4 is the same as between the pivots 8b and I5, and thedistances between the pivots I4-I5 and'43 are such that the pivot 43moves in substantially a straight line as the carrier is rocked aboutthe stationary pivots Ila-8b. The pivot axis 43 is equidistant from thepivot axes l4--I5. 'Ihe pull rod I is supported on the lblock 42 Ain anydesired manner to permit sliding of the pull rod on the block and tohold the pull rod against shifting off of the block sidewise. This maybe accomplished by forming a V-shaped pull rod receiving grooveextending lengthwise in the top of the block 42- in the mannerillustrated in my pendingV application, Serial No. 272,865. The block 42at its opposite extremes of motion abuts against the web of the T-shapedsupport 5 on one or the other of the pipes 3 to limit the 1ongitudinalmovement of the support 42v to an amount slightly in excess of theamplitude of the stroke of the pull rod I. To brace the foundation theposts 3-3 are secured together by a wooden strut 45 that bears againstthe supports 5--5 and is secured thereto by bolts 41, as may be seenfrom Figure l0.

The mode of operation of the carrier of Figure 9 is substantially thesame as that of the carrier of Figure 2 except that the rod I issupported only by the block 42,

Reference may now be had more particularly to Figures l1, 12, 13 and 14which show another embodiment of the. present invention. In thisconstruction the foundation 3 and the support 5 are the same asillustrated in Figure 3. The cross member Illa, which corresponds to thecross member I0 of Figure 2, is pivoted on the support 5 by meanssomewhat different from the struts I1 and I8 of Figure 2. The mountingfor the cross member Ia consists of a steel rod 49 bent to have a.horizontal portion 50 which is adapted to be extended through the bore 1of the support 5 and journalled therein. The rod is bent at 5I to form aportion 52 that extends upwardly and towards the center of the support5, as indicated in Figure 14, and is then bent to form three legs of atriangle, indicated at 54, 55 and 55. The part 56 is welded to the part54 at 51 to increase the rigidity of this structure. From the leg 5B ofthe triangle the rod continues, as indicated at 51, to and overlappingthe horizontal part "50 adjacent the curve 5I and is welded thereto, asindicated at 58, to strengthen the member and avoid bending of the part52 with respect to the `part 50 at the curve 5I when the carrier is inuse. The part 55 of the bent rod support is bolted to the cross member I@a in any desired manner as, for instance, by-two U-bolts 60 thatembrace the part 55 and extend through holes in the cross member Illaand are held in place by nuts 6I. Due to the welds at 51 and 58 it isapparent that the cross member Illa is supported rigidly and rmly by thebent rod, and immovable with respect to the part 50 thereof, which isjournalled in the support 5 by the cross member 59. A pair of pins 63-54are passed through aligned holes in the bearing part 50 to hold thatpart against sliding lengthwise in the bearing. A pair of identicalZ-shaped links 20' and 2 I', which correspond respectively to the links20 and 2| 'axes indicated at 61-68.

of these links comprises a steel rod bent into Z-shape, as illustratedin Figures 11 and 13, to provide a pair of horizontal bearing arms65-66. The upper arms of the two links 20-2I are extended through holesin the cross member a and journalled therein to swing about pivot axes|4-I5, respectively, whereas the lower arms of the two links areextended through holes in a cross Vmember 25 and journalled thereinabout The distance between the centers |4'-61 is the same as thedistance between the centers H-'68, The center of the part 50 aboutwhich the cross member 10a swings is equidistant from the pivot axes I4and I5.

The arms 6-5-66 of the links 20-2| may be retained against sliding outof their bearings in the cross member Illa and in the cross member inany desired manner as, for instance, by pins 'l0-1D that are passedthrough holes in the arms 65-66 on opposite sides of the link la and 25.

The pull rod l rests on the link 25 and is freely slidaole thereonlongitudinally of the link 25', and is held against movement sidewise ofthe link by two pairs of side by side bolts 4I-4l passing through thelink on opposite sides of the pull rod, in the same manner as in Figure8, and embracing the pull rod.

The centers of the holes in the cross member Illa for the centers |4-I5are located closer to the top of the cross member Illa than to thebottom thereof, whereas in the link 25 the centers 61--68 are locatedcloser to the bottom of the link than to the top thereof for the samereasons as in the structure of Figure l. The operation of the carrier ofFigure 12 is substantially the same as lthat of Figure 1. The limit ofmotion in one direction or the other of the car.- rier is reached whenone or the other of the links 21V-2|' abuts -against the part 51 of therod 49 in either direction of travel of the carrier from the centerposition. The stroke of the carrier is slightly greater than the strokeof the pull rod.

It is to be noted that the pull rod I may be bodily lifted ofi of thecarrier of Figure 11 and moved sidewise and lowered to the ground.

In compliance with the requirements of the patent statutes I have hereshown and described a few preferred embodiments of my invention. It is,however, to be understood that the invention is not limited to theprecise constructions here shown, the same being merely illustrative ofthe principles of the invention. What I consider new and desire tosecure by Letters Patent 1. Apparatus of the class described including aT-sbaped support, means for holding the stem of the T in position, and apull rod carrier pivoted on the web of the T-shaped support about anaxis extending lengthwise through the web.

2. Apparatus of the class described including a T-shaped support, meansfor holding the stem of the T in position, the web of the T having abore extending lengthwise therethroughy and a pull rod carrier pivotedon the support by means including a pivot memberextending through saidbore.

3. Apparatus of the class described comprising a pipe xed in a verticalposition, a T-shaped support the stem of which extends into and fitssnugly within the top of the pipe and the web of which projectshorizontally from the pipe, and a pull rod carrier pivoted on the web ofthe support about an axis extending horizontally lengthwise of the webof said support.

4. A straight line motion mechanism comprising a cross bar, side armspivoted to the ends ot the cross bar by means extending through the endsof the cross bar, converging members rigidly secured to the cross barand secured together, a pivot axis for the converging members locatedequal distances from the pivots of the side arms with the cross bar, alink, additional pivot axes connecting the respective side arms to saidlink, the distance between said additional pivots being greater than thedistance between the pivots of the side arms with the cross member.

5. A straight line motion mechanism comprising upper and lower Woodenbars, side arms pivoted to the upper and lower bars to form aquadrilateral -With the distance between pivots on one of the barsgreater than the distance between the pivots on the other bar, the pivotaxes extending through the bars and the bars constituting the bearings,and a stationary support, and means for pivoting the shorter of the twobars to the support about a single axis located equidistant from thepivot axes of the arms with said shorter bar.

6. A straight line motion mechanism including a first pair of spacedside bars, a second pair of spaced side bars, a cross member betweensaid pairs of side bars and pivotally connected at its opposite ends toone end of each pair of side bars, spacers between said cross member andthe side bars of each pair, pivot means including a pair of spacedpivots at the opposite ends of the side bars a fixed distance apartgreater than the distance between the pivots of the cross member,another pivot means a xed distance from the cross member and locatedequidistant from the axes between the cross member and the side bars,one of the two pivot means comprising a support for the mechanism andthe other comprising a support for a reciprocating object to be guidedin a straight line by the mechanism.

7. Apparatus for supporting a longitudinally reciprocating pull rodintermediate the ends thereof, said apparatus c-omprising straight linemotion mechanism including a rst pair of spaced side bars, a second pairof spa-ced side bars, a cross member pivotally connected at its oppositeends to one end of each pair of side bars, pivot means including a pairof spaced pivots at the opposite ends of the side bars a xed distanceapart greater than the distance between the pivots of the cross member,another pivot means a Ilxed distance from the cross member and locatedequidistant from the axes between the cross member and the side bars,the pull rod extending centrally between the bars of the rst pair ofside bars and between the bars of the second pair of side bars, one ofthe two pivot means comprising a support for the mechanism and the othercomprising a support for the pull rod to be guided in `a straight lineby the mechanism.

8. A straight line motion mechanism including a pair of links, a crossmember pivotally connecting the links at one end, a pair of spaced pivotmeans for the opposite ends of the links, means for maintaining thespaced pivot means a fixed distance apart greater than the distancebetween the pivots of the `cross member, stationary pivotal supportmeans a nxed distance from the cross member and located equidistant fromthe axes between the cross member and the links, the pair of spacedpivot means comprising a support for a reciprocating object to be guidedin a straight line by the mechanism.

9. A pull rod carrier for a reciprocating substantially horizontal pullrod of such length as to require support between its ends to preventexcessive sagging of the rod, said carrier comprising a pair of equallinks having parallel pivot axes at an end of each thereof, a third linkpivoted to said pair of links at said axes, a cross member pivotallyjoining the opposite ends of the links, the distance between the crossmember pivot axes being substantially less than the distance between thefirst mentioned pivot axes, means for supporting the cross member abouta single iixed pivot axis equidistant from the pivots between the crossmember and the links, said third link extending beyond its pivots withthe pair of links for engagement with a pull rod beyond said lastmelitioned pivots to prevent tilting of the third lin 10. A pull rodcarrier for a reciprocating substantially horizontal pull rod of suchlength as .to require support between its ends to prevent excessivesagging of the rod, said carrier being a straight line motion mechanismcomprising a pair of equal links and means for holding their ends afixed distance apart, said means including parallel pivot axes at theends of the links and a cross member pivotally joining the links; andmeans for pivoting the cross member about a stationary pivot axis at axed distance from the cross member and equidistant from the pivotsbetween the cross member and the links.

11. A pull rod carrier for a reciprocating substantially horizontal pullrod of such length as to require support between its ends to preventexcessive sagging of the rod, said carrier comprising a pair of equallinks and means for holding their ends a xed distance apart, said meansincluding parallel pivot axes at the ends of the links and a crossmember pivotally joining the links; and another pivot axis at a iixeddistance from the cross member and equidistant from the pivots betweenthe cross member and the links, said other pivot axis and the firstmentioned pivot axes being relatively movable with respect to oneanother in a straight line under the guidance of the cross member andthe said links, each of said links comprising two side by side memberslocated on opposite sides of the load supported by the carrier anddividing the stress of the load on the link between them, said crossmember comprising a beam each end of which is enlarged to form a headwhich is embraced by the side by side members of a link.

12. A pull rod carrier comprising a pair of equal link s, meansincluding a pair of parallel pivot axes connecting the links at one endand maintaining the links a xed distance apart at the connection, across member pivotally joining the links at their opposite ends, a rigidmetal member rigidly secured to and extending lengthwise of the crossmember, the ends of the metal member projecting from the cross memberand converging .towards one another and forming a frame, one end of themetal member extending at right angles to the cross member with thecenter of said one end located equidistant from the pivot axes of thelinks with the cross member and constituting another pivot axis, saidother pivot axis and the rst mentioned pivot axes being relativelymovable with respect to one another in a straight line under theguidance of the cross member and the said links.

13. A pull rod carrier for a reciprocating substantially horizontal pullrod of such length as to require support between its ends to preventexcessive sagging of the rod, said carrier comprising a pair of sets ofequal links and means for holding their ends a xed distance apart, saidmeans including parallel pivot axes and a cross member pivotally joiningthe sets of links and embraced by the links of each set; converging setsof supporting means rigidly secured to and embracing the cross memberadjacent to but spaced from the respective pivots between the crossmember and the links, and another pivot axis at the supporting means ata xed distance from the cross member and equidistant from the pivotsbetween the cross member and the links, said other pivot axis and theiirst mentioned pivot axes being relatively movable with respect to oneanother in a straight line under the guidance of the cross member andthe said links.

14. In a straight line motion mechanism a cross bar, a pair of strutsone end of each of which is secured to the cross bar at one end thereofand dverging from one another, a second pair of struts one end of eachof which is secured .to the cross bar at the opposite end of the crossbar and also dverging from one another, means securing the opposite endsof the two pairs of struts together, said means including means formaintaining said opposite ends of the struts of each pair spaced apartan amount in excess of the thickness of the cross bar.

15. A straight line motion mechanism comprising four links pivotedtogether to constitute a quadrilateral, two opposite links being ofequal effective lengths and the other two being of unequal effectivelengths, means for pivotally supporting the shorter of the unequal linksto swing about a single xed pivot axis, the longer of the two unequallinks extending beyond each of its two pivotal connections in thequadrilateral for engaging, beyond those two pivotal connections, anobject to be guided by the mechanism.

16. In combination with a substantially horizontal reciprocating pullrod, a carrier supporting the rod intermediate its ends and comprising astraight line motion mechanism pivoted about a single stationary axisand including a link and means supporting the link about two spacedparallel and movable axes which are constrained by the mechanism to astraight line horizontal motion only while the two movable axes are heldat the same horizontal levels, said link having means engaging said pullrod at locations spaced apart a distance greater than the'distance be-.tween said movable axes whereby the rod prevents vertical tilting ofthe link to move either movable axis below the other movable axis.

17. In combination with a substantially hori- Zontal longitudinallyreciprocable pull rod, a carrier supporting the rod and comprising meansfor supporting a pair of spaced movable pivots a xed distance apart andconstraining the movement of the pivots to an arcuate path having onexed center, a pair of equal links pivotally supported by and swingableabout said movable pivots, a third link pivotally connecting andsupported by the said pair of links, and pull rod supporting meansconnected to the third link, said third link extending beyond the pivotsbetween it and the rst two links and engaging the pull rod on oppositesides of the carrier a distance apart greater than the distance betweenthe pivotal connections of the third link with the two first mentionedlinks, whereby the horizontal pull rod maintains said third link againsttilting out of the horizontal position.

ALLEN M. ROSSMAN.y

